The overall objective of this project is to define deviant spatio- temporal patterns of cortical event-related potentials (ERP) in children with specific subtypes of developmental language disorders (DLD). It has been shown that ERPs recorded during the performance of tasks that tap specific linguistic operations show distinct spatio-temporal patterns of activity reflecting the underlying mechanism. subserving these functions. The linguistic operations to be tapped include phonemic discrimination, phonemic identification and the discrimination of meaningful words along semantic and verbal pragmatic dimensions. It is postulated that these ERP probes of linguistic processing will show patterns of dysfunction that are related to the language processing deficits of children with specific subtypes of DLD. These are intended to provide objective indices of regional cortical dysfunction for each subtype. The children to be studied in this project are drawn from the longitudinal cohort (Project I) and have been clinically, identified and neuropsychologically characterized as DLD and higher functioning ASD subtypes. In addition, a cohort of children at high risk for cognitive and language dysfunction due to extreme prematurity or other perinatal insults, who have received electrophysiologic testing from birth, will participate in this study. These children, who are now between 6-8 years of age, show a high incidence of language dysfunction. The normative sample will include the normal full term control group for the high risk sample who have also undergone electrophysiologic assessments from birth and an additional group of children recruited from local primary school. Thus, the ERP profiles of the DLD, ASD and normal children will provide external validation of the clinical subtypes, and in combination with the other external validation measures (MRI and genetic markers), may reveal new groups of children with specific patterns of abnormalities. Finally, the abnormalities of the spatio-temporal characteristics of the neural activity recorded from the DLD and ASD children may help to elucidate the pathophysiology of these disorders.